Modern firearms typically use cartridges consisting of metal cases holding a projectile placed over a smokeless propellant charge with a primer used as the ignition source. When the primer is struck it ignites the propellant and fires the projectile. The expended cartridge is then ejected either manually or automatically prior to the next cartridge being loaded and fired. Typically a metal cartridge can be reused while the fired projectile cannot. A muzzleloader firearm is a type of firearm that requires multiple ammunition components to be loaded down the front end of the barrel, also known as the muzzle. Before each and every shot a typical muzzleloader user must load a propellant charge and a projectile down the muzzle of the firearm. The ignition source for muzzleloader firearms can vary greatly ranging from primers and percussion caps to a traditional flintlock design. The propellant charge is loaded into the barrel in either a granular form or as a premeasured consolidated pellet form.
Most muzzleloader propellant charges are hygroscopic compounds. Therefore an unsealed propellant charge may allow moisture to be absorbed into the propellant charge. Propellant moisture absorption may cause inconsistent ignition, reduced accuracy, inconsistent velocity and firearm corrosion. Furthermore, moisture absorption may cause the propellant burn rate to be reduced thereby altering pressure and velocity characteristics of the firearm.
U.S. Pat. Pub. 2014/0090285 A1 describes a muzzleloader bullet system including a pre-packaged propellant charge and a primer for providing efficient loading and unloading of the muzzleloader. U.S. Pat. Pub. 2012/0318123 A1 describes an encapsulated propellant charge for a muzzleloader.